1. Field of the Invention
The present invention relates to a method of producing an aperture electrode member for use in an image forming device such as a facsimile machine, a plotter, a printer, or a copy machine.
2. Description of Related Art
U.S. Pat. No. 3,689,935 discloses an image forming device including an aperture electrode member, a biasing member, a toner supply member, and a medium supply unit. The aperture electrode member includes a substrate a reference electrode formed on a first surface of the substrate, and a plurality of electrodes formed on a second surface of the substrate which is opposite from the first surface. The substrate is formed from an electrically insulated material. The plurality of control electrodes are electrically insulated from each other. The aperture electrode member is formed with a plurality of apertures arranged in a row. Each aperture corresponds to one of the control electrodes and completely passes through the corresponding control electrode, the substrate, and the reference electrode.
The biasing member is provided for selectively applying voltages to the reference electrode and the control electrodes so that an electrical bias is generated between the reference electrode and the control electrodes. The toner supply member is positioned confronting the second surface of the aperture electrode member for supplying electrically charged toner particles to the aperture electrode member. The toner particles supplied from the toner supply member are selectively pulled through the apertures as controlled by the bias developed between the control electrodes and the reference electrode. Then the toner particles that passed through the apertures impinge against a recording medium supplied by the medium supplying unit. In this way a desired toner image is formed on the recording medium.
The Japanese Patent-Application Publication (Kokai) No. HEI-6-79907 also discloses an image forming device including an aperture electrode member, a toner supply roller, and a frame. The aperture electrode member is formed with apertures and includes a plurality of control electrodes provided on a surface of the aperture electrode member. The frame supports the aperture electrode member at its surface. The toner supply roller is positioned in contact with the surface of the aperture electrode member for supplying toner particles to the apertures. In order to supply a uniform amount of toner particles to the apertures, the toner supply roller needs to uniformly contact the aperture electrode member especially at portions near the apertures.
The above-described aperture electrode members are produced by processes described below.
First, a substrate is formed from an electrically insulating material, such as a polyimide. Then control electrodes are formed by forming a copper film pattern on a first surface of the substrate.
Next, an excimer laser is irradiated onto the substrate to induce ablation reaction. As a result, apertures penetrating both the substrate and the control electrodes are formed. Thus formed apertures can have an extremely clean shape. However, the ablation reaction generates carbon particles, and these carbon particles cling to the substrate, specifically, on the surface surrounding the apertures and on aperture side walls defining the apertures. The carbon particles are removed from the substrate by ultrasonic cleaning methods or plasma etching methods.
If static electricity is generated in the aperture, toner particles will not pass through the apertures but will instead cling onto the aperture side walls, thereby clogging the aperture. Therefore, a charge prevention coat layer is formed for preventing static electricity from being generated in the aperture. The charge prevention coat layer is formed on the aperture side walls by introducing a coat liquid into the apertures. The coat liquid is polyimide ink with carbon particles dispersed therein.
However, in the above-described processes, the coat liquid introduced into the apertures may completely close up the apertures. Also, the coat liquid may overflow out of the apertures and cling onto the surfaces of the substrate. When the coat liquid dries and hardens, the coat liquid makes rough and uneven bumps on the surfaces of the substrate around and in the apertures.
When an aperture electrode member with such uneven surfaces is used in the image forming device of Japanese Patent-Application Publication (Kokai) No. HEI-6-79907 described above, the toner supply roller will not uniformly contact with the aperture electrode member. This prevents the toner supply roller from uniformly supplying toner particles to the apertures.
Further, because only the aperture side walls are covered with the charge prevention coat layer, toner particles contact a different kind of material, that is, the surface of the substrate and the charge prevention coat layer, after being supplied to the aperture electrode member until impinging on the recording medium. This prevents precise control of flow of toner particles through the apertures.
It is an objective of the present invention to overcome the above-described problems and also to provide a method of producing an aperture electrode member without closing up apertures with coat liquid.
It is another objective of the present invention to provide an aperture electrode member capable of uniformly contacting at area around apertures with a toner bearing roller and a method of producing the aperture electrode member.
It is still another objective of present invention to provide an aperture electrode member capable of precise control of flow of toner particles through apertures.
In order to provide the above and other objectives, there is provided an aperture electrode assembly for use in an image forming device including a recording particle supply unit for supplying electrically charged recording particles for the aperture electrode assembly. The aperture electrode assembly including a substrate and a plurality of electrodes. The substrate is formed with a plurality of apertures through which electrically charged recording particles pass through. Each of the plurality of apertures is defined by an aperture side wall. The substrate has a first surface and a second surface. The first surface of the substrate is covered with a first layer, and the aperture side walls is covered with a second layer. The substrate is designed to be positioned so that at least a portion of the first surface is in intimate contact with the recording particle supplying member. The first layer and the second layer are formed from a same material. The plurality of electrodes are provided on the second surface of the substrate for respective ones of the plurality of apertures.
There is also provided an image forming device including a recording particle supply unit, an aperture electrode assembly, a frame, and a control unit. The particle supply unit supplies electrically charged recording particles. The aperture electrode assembly includes a substrate and a plurality of control electrodes. The substrate has a first surface coated with a first layer and a second surface. The substrate is formed with a plurality of apertures each defined by an aperture side wall coated with a second layer. The plurality of control electrodes are provided on the second surface of the substrate for respective ones of the plurality of apertures. The first layer and the second layer are formed from a same material. The frame supports the aperture electrode assembly such that at least a portion of the first surface is in intimate contact with the recording particle supply unit. The control unit generates an electric field between the recording particle supply unit and selective control electrodes so that the electrically charged recording particles are selectively pulled through respective apertures toward the selective control electrodes due to an electrostatic attraction of the electric field.
Further, there is provided a method of producing an aperture electrode assembly. The method includes the steps of a) forming a plurality of electrode members on a first surface of a substrate, b) forming a plurality of apertures penetrating the substrate and respective ones of the plurality of electrode members, the plurality of electrode members formed with corresponding ones of the plurality of apertures defining a plurality of electrodes, the plurality of apertures being defined by aperture side walls, c) applying coat liquid onto a second surface of the substrate and into the plurality of apertures from a second surface side of the substrate; and d) drying the coat liquid so as to form a coat layer over the second surface and the aperture side walls.